!   C06LBF Example Program Text
!   Mark 27.3 Release. NAG Copyright 2021.

    Module c06lbfe_mod

!     C06LBF Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: f
!     .. Parameters ..
      Integer, Parameter, Public       :: nin = 5, nout = 6
    Contains
      Function f(s)

!       .. Function Return Value ..
        Complex (Kind=nag_wp)          :: f
!       .. Scalar Arguments ..
        Complex (Kind=nag_wp), Intent (In) :: s
!       .. Intrinsic Procedures ..
        Intrinsic                      :: cmplx
!       .. Executable Statements ..
        f = cmplx(3.0E0_nag_wp,kind=nag_wp)/(s**2-cmplx(9.0E0_nag_wp,kind=     &
          nag_wp))
        Return
      End Function f
    End Module c06lbfe_mod

    Program c06lbfe

!     C06LBF Example Main Program

!     .. Use Statements ..
      Use c06lbfe_mod, Only: f, nin, nout
      Use nag_library, Only: c06lbf, c06lcf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: b, epstol, exact, finv, pserr,       &
                                          sigma, sigma0, t
      Integer                          :: ifail, j, m, mmax
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: acoef(:)
      Real (Kind=nag_wp)               :: errvec(8)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: abs, exp, real, sinh
!     .. Executable Statements ..
      Write (nout,*) 'C06LBF Example Program Results'
!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) mmax
      Allocate (acoef(mmax))
      Read (nin,*) sigma0, epstol, sigma, b

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
      ifail = 0
!     Compute inverse transform
      Call c06lbf(f,sigma0,sigma,b,epstol,mmax,m,acoef,errvec,ifail)

      Write (nout,*)
      Write (nout,99999) 'No. of coefficients returned by C06LBF =', m
      Write (nout,*)
      Write (nout,99998) ' ', 'Computed', 'Exact', 'Pseudo'
      Write (nout,99998) 't', '    f(t)', ' f(t)', ' error'
      Write (nout,*)

!     Evaluate inverse transform for different values of t
      Do j = 0, 5
        t = real(j,kind=nag_wp)

        Call c06lcf(t,sigma,b,m,acoef,errvec,finv,ifail)

        exact = sinh(3.0E0_nag_wp*t)
        pserr = abs(finv-exact)/exp(sigma*t)
        Write (nout,99997) t, finv, exact, pserr
      End Do

99999 Format (1X,A,I6)
99998 Format (1X,A10,A15,A15,A12)
99997 Format (1X,1P,E10.2,2E15.4,E12.1)
    End Program c06lbfe